Titanium oxide-containing films exhibit various functions such as UV-cutting property, self-cleanability, ultra-hydrophilic (anti-fogging) property, anti-reflecting property, heat resistance (flame retardant), abrasion resistance, electrical insulating property and dielectric characteristics, and have therefore been intended to be used in various applications.
In general, titanium oxides conventionally used are of either an anatase type or a rutile type, i.e., titania, and have been used to prepare a coating material in the form of a dispersion of titania having a particle size of from 10 nm to several hundreds nm. In addition, a titania precursor obtained by hydrolysis of a titanium alkoxide is baked on a substrate to form a titania-containing coating film thereon.
Further, there have been reported coating films containing not conventional titania of either an anatase type or a rutile type but titanates (for example, refer to T. Ohya, A. Nakayama, T. Ban, Y. Ohya and Y. Takahashi, “Bull. Chem. Soc. Jpn”, Vol. 76, p. 429 (2003)). According to this report, a glass substrate is spin-coated or dip-coated with a transparent aqueous solution obtained by reacting an organic cation such as tetramethyl ammonium hydroxide and diethanol amine with titanium tetraisopropoxide to form a relatively transparent titanate-containing coating film.